Genitalic morphology and copulatory mechanism of the scorpionfly Panorpa jilinensis (Mecoptera: Panorpidae)

Abstract

Specific genitalic morphology reflects vital sexual functions in insects and examination of genitalic structures is important in understanding copulatory mechanisms. The morphology of male and female genitalia was investigated in the scorpionfly Panorpa jilinensis using light and scanning electron microscopy. The male genitalia are located between the epandrium and hypandrium of the ninth abdominal segment. The hypandrium comprises a broad basal stalk and two long hypovalvae. The gonopods are two-segmented, each consisting of a basal gonocoxite and a distal gonostylus. The parameres are Y-shaped, with a basal stalk and two apical branches (ventral and dorsal parameres), each of which terminates into a flattened lobe. The aedeagus bears a pair of well-developed ventral and a pair of small dorsal valves with the phallotrema situated centrally. In the female genitalia, the subgenital plate is emarginated in a V-shape at the distal end and seems to be paired in the origin, with the gonopore (the opening of the common oviduct) at its base. The genital plate is composed of a plate, two long posterior arms, and a long broad axis, the ventral groove of which bears the spermathecal duct. The copulatory pore (the spermathecal opening) is situated medially at the posterior end of the genital plate. Based on the morphology of the male and female genitalia and mating behaviour observations, the copulatory mechanism of P. jilinensis is briefly discussed.